1. Field of the Invention
This invention relates generally to apparatus for cleaning loose fill media, and more particularly to apparatus for cleaning loose fill media of the type used in aeration, degasification, odor control and air stripping towers.
2. Description of Related Art
A widely used method for removing contaminents from liquids or gases is to pass liquid down through a tower containing loose fill or random pack media which causes the liquid to separate into drops. As the liquid descends in the tower, gas is passed in reverse flow through the tower from the bottom so as to intimately contact the liquid. The particular loose fill media and the liquids and gases which are used in a tower are selected in accordance with the liquid or gas to be decontaminated and the contaminents contained therein.
The towers may be constructed of various materials such as stainless steel, aluminum or fiberglass. The loose fill media is typically fabricated of polypropylene, polystyrene, stainless steel, etc. It is intended by the use of these materials that the inside surface of the tower and the loose fill media will not become fouled by the liquid being cleaned nor the contaminents being removed. Despite this intent, the loose fill media eventually becomes so fouled and clogged that the tower will no longer effectively perform its function. At this time, the loose fill media is removed and generally discarded, to be replaced with new loose fill media.
The loose fill media has a large volume and low density foraminated structure, and is available in various sizes. The contaminents which foul the loose media are susceptible of being removed, but the many crevices of the media make cleansing difficult. Placing the media in a bath of a suitable solvent is not effective because many of the types of media float, leaving surfaces which are not exposed to the solvent. Moreover, mere soaking is not effective for contaminent removal.
Although large quantities of the loose fill media are used in a typical tower, the difficultly in economically cleaning the media has caused much of the media to be discarded once it becomes contaminated.
In the past various devices have been disclosed for the treatment of bulk materials such as by washing, separating or exposing to other materials.
U.S. Pat. No. 402,845, Loughran, entitled "Gravel Screen", discloses a cylindrical screen which is rotated and inclined so that gravel introduced at the higher end will move to the lower end. Buckets at the lower end raise the gravel to a chute to remove it. The cylindrical screen is partially immersed in a tank of water.
U.S. Pat. No. 468,247, Jewett, entitled "Machine for Washing and Grading Gravel", discloses a cylindrical screen with a hopper positioned above the screen. Gravel is deposited in the hopper and is moved onto the screen impelled by water. Finer gravel passes through the screen and onto an interior chute to be removed at the end of the cylinder. Coarse material is carried on the outside of the cylindrical screen and falls off. The screen tends to rotate due to the impinging water and gravel.
U.S. Pat. No. 483,030, Volstorf, entitled "Rotary Pulp Strainer", discloses an annular strainer which is inclined and partially submerged in a tank of liquid. Pulp material is fed to the lower portion of the strainer through a central funnel and moves upward on a helical blade as the cylinder rotates, and is then discharged.
U.S. Pat. No. 3,133,832, Pellhammer, entitled "Impregnation of Fibrous Material", discloses an outer rotating drum surrounding an inner fixed drum with fibrous material carried around the annular space by the outer drum. The drum is immersed in a liquid which impregnates the fibrous material.
U.S. Pat. No. 3,392,828, Muller, entitled "Separation of Substances", discloses an inclined, rotating cylindrical screen in which materials of different sizes and densities are separated. Lighter particles are carried out with liquid, smaller dense particles pass through the screen and are collected in a hopper and large particles are carried by vanes to be deposited on a chute.
U.S. Pat. No. 3,909,291, Leong, entitled "Comestible Cleaning Apparatus", discloses a cylindrical wire mesh basket which is rotated in a tank of water. Bean sprouts to be cleaned are placed in the basket. The floating bean sprouts are struck by vanes in the basket causing debris to separate and be carried off.
U.S. Pat. No. 4,184,944, Tytko, entitled "Rotary Screen Appliance", discloses a cylindrical screen for sifting sand which can be secured to a cement mixer for rotation therewith and permits tilting of the screen for dumping the residue.
The foregoing devices are typically designed to provide a continuous operation wherein new material to be processed may be continuously introduced at one location, and the already processed material is continuously expelled at another location. These structures do not accommodate the cleaning of materials wherein different materials may be held in separate steps of the cleaning process for times which can be modified as necessary for effective cleaning.
It is therefore an object of this invention to provide loose fill media apparatus which provides immersion of the media in an appropriate solvent for a time which can be controlled by an operator and which also provides a spray washing and rinsing of the media while it is not immersed for time which can be controlled by an operator.
It is a further object of this invention to provide apparatus which will tumble the media either intermittently or continuously for times which can be controlled by an operator to enhance the effectiveness of the spray washing.
It is also an object of this invention to provide apparatus which has a foraminated cylinder which can be moved between an immersion position and a position for spray washing and media removal.
In accordance with these and other objects, which will become apparent hereafter, the instant invention will now be described with reference to the accompanying drawings.